This insight follows on from an earlier article where I identified that the business rule “when an employee leaves the organisation, all their assets must be returned” was part of the domain model, and not just a matter of cleaning up foreign keys in the database.

I originally implemented this rule as part of a dedicated domain service called IPersonTerminatorService. Later on, I refactored it out into a standalone IAssetReturnerService to satisfy the single-responsibility principle.

But this morning I realised something: in real life, it’s the employee himself who returns all his stuff — not some other process. By taking this responsibility away from the Employee class I’ve committed two sins: creating a fictional concept in the domain, and reducing the capabilities of the Employee (leading to an anemic data-only domain model).

Time to give this responsibility back to the employee:

January 29, 2009

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